This program represents a multidiscipline approach to the study of reproductive endocrinology by the means of ultrastructure analysis, radioimmunoassay, isolated organ perfusion, in vivo studies and in vitro incubation. The hypothalamo-pituitary-ovarian axis and uterus during the ovarian cycle and through implantation will be examined by a group of investigators to determine the regulation of synthesis, secretion, metabolism and mechanisms of action of hormones that control early reproduction.